Zach Mainen:“We create this incredibly complicated illusion of the real world that is what we experience all the time”

It is a part of every waking moment of our lives. But whenever scientists have tried to study it, consciousness has slipped through their fingers. Will we ever understand why we have it and how it arises in our brains?

The problem of consciousness is still mainly a question being tackled by philosophers, but neuroscience is starting to slowly get a grip on it, says Zach Mainen, principal investigator at the Champalimaud Centre for the Unknown, in Lisbon, Portugal.

At his lab, Mainen has been studying, for example, the sense of so-called “subjective confidence” – the feeling of confidence one has in the validity of one’s choices – … in rats! Many people might never have imagined that these small animals could be capable of experiencing something akin to this.

These and many other experiments are contributing to show that consciousness, in the general sense, is not uniquely human. Even computers may one day become conscious. Nonetheless, it is also clear that human consciousness has a quality that other consciousnesses do not possess…

We asked Zach Mainen to tell us more about this intriguing brand of science, and also to share with us some of his thoughts on the bizarre nature of the conscious experience we all take so much for granted but which is in fact so mysterious.

What is consciousness?

Consciousness is the first-person experience of the world. It’s what’s happening as seen from the inside of our heads.

How come we have it?

The hard question about consciousness is exactly that. It’s not what’s it like, it’s why is there any such thing. I actually take a slightly unusual view. I flip the question around and say: it’s a given I have experience. When I wake up in the morning, before I open my eyes, here I am, experiencing something.

“Consciousness is the first-person experience of the world. It’s what’s happening as seen from the inside of our heads”

Now the question becomes: why does there seem to be a real world outside, that is still there every time I wake up, that is filled with other people that seem to be like me – how is all of this created?

Most people start by saying that there’s this physical world, that the Universe is five billion years old, and then ask how did this gave rise to all these little consciousnesses. But I don’t think it makes more sense to start from there than to start the other way.

Either way you start, there seems to be a big gap between the physical universe, that has these objective properties, and one’s own feelings, sensations – this inner world that no one else has any access to. These two things seem to have nothing to do with one another.

Does that mean there’s nothing much to be said about this “hard problem” of consciousness?

On the contrary, I think the hard problem of consciousness is the most interesting question there is, but it’s still very much a philosophical problem – a problem for buddhistic monks and philosophers, not a problem that neuroscientists are working on.

The existence of consciousness is not something that I think we’re making much progress on from a scientific sense in neuroscience. But there are other aspects of consciousness for which there is more to be done in a scientific sense.

How do you objectively study something as subjective as consciousness?

What’s very interesting is that, although we can’t explain why consciousness exists, if you take any particular experience that someone might have, any particular aspect of their conscious experience, you can ask them about it and they can tell you about it.

Actually, if you’re really good psychologist, you can get very specific and can ask people to make minute distinctions between the types of experiences that they have – very complex experiences, complicated thoughts or obscure experiences, altered states – anything! You can help them to reduce those experiences to something they can report.

Take color vision. In principle, if I am interested in your subjective experience of color, I could tell whether you’re color-blind or not, whether you perceive the same as me. I could tell about all sort of details of your color vision.

“I think the hard problem of consciousness is the most interesting question there is, but it’s still very much a philosophical problem”

In any one experiment, I can only be looking at one little thing, so it’s not like I can know the whole content of your experience. But if I’m a careful scientist, I can actually expose the deepest inner workings of your subjective experience of color. I can get really, really far in there.

And what’s interesting is it turns out that there is this amazing correspondence between whatever is going on inside anyone’s head and stuff one can measure externally if one’s careful enough.

That’s another mystery in itself: it’s not just that there is consciousness and it’s separate from physical matter, but also that there’s this amazingly precise correspondence, where whatever it is that we happen to have inside our head is mirrored in something that is measurable from outside.

And I’m not even talking about sticking electrodes through your skull, just about carefully manipulating you to tell me what’s going on inside your head. You can get an awful lot of information by just being a very good psychologist about human behavior.

Cuttlefish and “theory of mind”

One of the hallmarks of human consciousness is the so-called “theory of mind”, which essentially means we are able to put ourselves in somebody else’s place. Do animals have this capacity?

This is a pretty interesting thing, I agree, and it sounds quite sophisticated. But is it unique to humans? I think the answer is no. And it’s not just “no, of course great apes can do it”. Mollusks – and we’re talking about octopus and cuttlefish, stuff we eat all the time [laughs]–, they also do it.

There are experiments showing that. Cuttlefish are masters of camouflage. So you take a cuttlefish, and you put it in a box with a wall that has a pattern and a floor with another pattern. And then, you put a predator somewhere out there. And what the cuttlefish does depends on where the predator is. If the predator is down here [points to near the bottom], then the cuttlefish fish will adopt the pattern of the back wall of the box. If the predator is up here, then the cuttlefish will adopt the pattern for the floor. This means the cuttlefish seems to infer the other fish’s viewpoint – it seems to put itself in the mind of the predator and adopt the correct coloration to camouflage itself.

“Cuttlefish and people have almost nothing in common in their nervous systems. But they have something I think you can call this a basic element of a theory of mind”

Cuttlefish can also control the two sides of their body’s coloration separately. And there’s another experiment, which is a bit similar, where you have the cuttlefish swimming along and he’s courting a female.. and the male cuttlefish will show his nice normal pattern on the side facing the female. But if on its other side some other fish comes up, he will show his “angry” side only to that fish so that the female can’t see it. He wants to be a nice guy [laughs] and not be seen to be too upset. It’s completely crazy! Cuttlefish and people have almost nothing in common in their nervous systems. They’re practically insects! But they have something I think you can call this a basic element of a theory of mind.

I think that when we look at any specific ability that we like to call human, which seems complicated and quite mysterious, if we put it under the lens of a really tight experiment and look at other species, we can find animals also have it. The bottom line is that a lot of things that seem complicated, and especially the stuff we like to think is really special about us, doesn’t turn out necessarily to be that complicated or that special. In some ways, whenever neuroscience “explains” something, it challenges our specialness a little bit.

Can you give us another example?

A topic that we work on in my lab is “subjective confidence”. This is basically the feeling of confidence one has in the validity of one’s choices or predictions. We started studying this in rats a few years ago. And yes, rats have something like subjective confidence. You ask a rat to make a left-right decision, and you make it hard or easy, and then after they made the decision, you ask them to wait to get the result of the decision, which is to get water or not. If they’re more confident, they will wait longer, and if they’re less confident they will wait less long.

Basically, they show the same pattern of behavior that humans show when asked the same kind of question. So they have what we would call a sense of confidence and it functions at the behavioral level in a very similar way to that of humans. And there’s also evidence that probably some of the same brain areas are involved. It’s amazing, isn’t it?

So what’s special about human consciousness?

Some of the things that make us uniquely human are relatively long lifespan, and our very good memories – that is, the remarkable fact that we can remember events from many, many years ago, which can trigger emotions that almost bring us back in time.

I think our memories are an interesting ability that not all animals have – or at least we can’t tell whether they have. This long lifespan also goes along with very extended planning, thinking about the future with the wisdom of years. All those qualities, extended life and extended experience, the ability to think far into the future and care about it, give qualities to our experience that are different from that of animals which will be gone in a year. And that makes our lives very, very different. These longer timescales give a richness and a quality to our existence that doesn’t exist otherwise.

Another thing that’s worth mentioning – and I think it’s under-appreciated in neuroscience – is our ability to talk and write about our experience and to hand that down to our children. To have a history. That really shapes our world. The perception of our own lives is shaped by the fact that we read books that have stories that tell about life. They shape the way we interpret our own experiences.

It’s incredibly important, that aspect of who humans are. We’re deeply cultural, we’re deeply social beings that are experiencing things indirectly through culture. We inherit not only genes, we inherit culture, and the culture shapes how we think about ourselves and how we experience. That this socio-cultural dimension is a big dimension of our consciousness.

ROBOTS AND DREAMS

Do you think it would be possible to make a conscious robot?

Good question! I think we’re going to make computers that pretend to be human. Will they be conscious? Well, we don’t really have a test for consciousness. There are tests that have been proposed, like the Turing test, but the Turing test is a practical thing: it just states that if a computer can fool you into thinking it was human, then it is human.

But it could still be fooling you and not be really conscious.

Yes, right. But if it’s good enough to fake it, then how will I ever know? You could say it will always be a computer, it will never have a biological origin, it will always in some way always be called out, “hey, you’re not a real person, you’re a machine!” .

“We inherit not only genes, we inherit culture, and the culture shapes how we think about ourselves and how we experience.”

People are clearly going to make things that get closer to seeming conscious. And functionally, things will get closer and closer to human. But structurally – if you look behind the curtains – they won’t be. So there’ll be this weird contradiction between something that seems so very, very human – and I’d like to think that it is – but at the same time… it’s just a machine!

I think we are going to be really tearing ourselves apart about this. Will they really deserve rights? Come on, they’re not flesh and blood! But the fact is, we’ve been granting more and more rights, and recognizing the similarity to us of a broader range of things.

It will be like this back and forth between people who think it’s completely ridiculous to think that a machine could be conscious like us and others who think it’s completely ridiculous to deny the obvious similarity. It’ll be very interesting and I think this will be a big deal in the next ten, 20 years. It’s coming – it’s almost on top of us already.

We all feel as if we have an endless ”stream” of consciousness, an endless movie inside our heads that seamlessly creates the scene we perceive as the outside world. Could this simply be an illusion constructed by our brains?

We seem to have a very rich, instantaneously available, particularly visual, world. We seem to see a very big world in front of us. But there are some very good experiments which show that it’s less true than we think it is [laughs], and that there’s not actually that much that’s ever happening at any particular instant in your consciousness. So the impression of the whole scene is an illusion.

You can show this by changing something in the scene while the person is staring right at it. This is called “change blindness” and all it takes is something very subtle to distract the person from noticing the onset of the change. So say if there is a flicker of the image or some other kind of interruption, the person will fail to notice that some object right in front of them has appeared or disappeared. The effect is quite stunning.

In real life, your visual scene seems to be complicated, there seems to be a lot going on, but that is because we’re building the scene up over a minute or many seconds, looking around and keeping that in memory. We do not appreciate the entire scene instantaneously, it’s stitched together from saccades – eye movements –, which happen over a sequence of time.

So what exactly is in our consciousness?

At any particular instant, there’s really very little going on in our consciousness and it’s very simple. What’s complicated is the sequence of things that happen and that we put together. It is through the sequence that we put together a story.

And because a big part of our experience relies on this flow and the stitching together of different moments, alterations in that can cause very interesting changes.

It makes me think about dreams. One of the characteristics of dreams is that things are disjointed in time. You may look and somebody’s there, you look away and back and then nobody’s there. So I think part of the quality that gives dreams their weirdness is that, though the instants are fairly normal, this kind of unexplained changes from moment to moment is what makes them bizarre.

“At any particular instant, there’s really very little going on in our consciousness and it’s very simple. What’s complicated is the sequence of things that happen and that we put together. It is through the sequence that we put together a story”

A stunning thing, by the way, is that anyone who has had even limited experience of dreams can only be amazed that so much of what constitutes our experience is entirely created by what’s inside our head, without any necessary input from the world.

True, dreams are not exactly the same as reality, but have you never woken from a dream being almost convinced that it was real? Sometimes you wake up and wonder: “how on earth did I fabricate this thing?” Making up scenes, making up people, making up…

So all this in our head is enough to fool us – not only dreams, but our experience of the world itself.

To me, that’s one of the great mysteries of consciousness: the fact that we create this incredibly complicated illusion of the real world – kind of a simulation – that is what we experience all the time.

And what’s even more mysterious is that we’re sharing the same illusion – because if I’m making it up, then how come I’m not living in a different world from yours? How is it that we can somehow interact and that we seem to be talking about pretty much the same world all the time?

It’s really amazing to think we are in this mirrored consensual illusion of the same physical reality, a lot of which is just what’s going on inside our heads.

Ana Gerschenfeld works as a Science Writer at the Science Communication Office at the Champalimaud Neuroscience Programme